NPS 14 Thru 24 CL2500 RTJ Ring Gaskets

[bwfs]

Does anybody can help me out?
I am looking for RTJ Ring Gaskets for NPS 14 Thru 24 flanges with design pressure 5000 psi @ 400 degree F. Per ASME B16.5, the allowable pressure for CL 1500 is less than 5000 psi.
As 14"-24" CL2500 flanges are not listed in any Codes, the high pressure flanges need to be designed per App.2 of ASME VIII DIV.1 or other methods. Can we use the CL 1500 RTJ Ring gaskets? For example, use gasket R63 for 14" flange; use R67 for 16" flange; R71 for 18" flange; R75 for 20" flange; R79 for 24" flange under 5000 psi, 400F condisiton.
Thank you for your response in advance.

 

[brkmech1234]

If the design + staic head is less than the flange rating you can use 1500 rating as well. Since the values so close, please have a thorough check. If the design aspect is OK, you need to get client appproval so that he does have any issue with his piping.

 

[bwfs]

Brkmech1234, thank you for your valued input.
Let me take a example for this: We have a pressure vessel, design pressure 5000 psi at 400 deg F. all other nozzle sizes less than NPS12" (these nozzles will have piping connections,) we can select 2500# flanges per ASME B16.5, and there are 2500# RTJ ring gaskets available as well. For 2500# flanges, MAWP will have about 5280 psi at 400 deg F. Now we need a access inspection opening NPS 14", but 14" 2500# is not listed in ASME B16.5. For this flange we can design per Appendix 2 of ASME VIII Div.1, but there is no 14" 2500# RTJ ring gasket available. Can we use a standard 14" 1500# RTJ ring gasket? if not what standard/ code can we follow to design a gasket that allows 5000 psi? (Note: the MAWP of 14" 1500# flange is about 3170 psi at 400 F.)

 

[brkmech1234]

bwfs,
You can use 14" 1500# gasket if the gasket dimensions has been considered in design of flange as per ASME VIII Div2 .

 

[brkmech1234]

Corresction to above post:

Please read it as ASME VIII Div1 .

 

[bwfs]

brkmech1234, thank you very much for your reply.
Based on what you said, through 14" 1500# RTJ ring gasket is for 14" 1500# flange (say the MAWP of the flange is 3170 psi at 400 F for SA105 material), the gasket itself can have pressure rating greater than 5000 psi. Do you have any reference support this?

 

[brkmech1234]

It seams that you are at basic level of designing. Gasket does not have pressure rating truly as far flange design concerned. I suggest that you perform a manual calculation of flange as per Appendix 2. Then you will have more clarity.

 

[bwfs]

You mean we can select either 14" 150#, 300#, 600#, 900#, or 1500# RTJ ring gasket for a 14" 2500# flange (w/ blind) designed per Appendix 2? That seems doesn't make sense. Looking forward to your reply. Thank you!

 

[brkmech1234]

bwfs,

As far as appendix 2 is concerned, rating of the gasket (dimensional standard) does not matter. It is concerned with ID and OD and gasket properties. You can use any dimensions of gasket (non standard) with a condition that the gasket should lie between flange id and bolting.


My explanation is not making any sense to you because you did not know what is there in appendix 2.

 

[ricklts]

Since there is no standard for 2500# flanges above 12" NPS, you might want to take a look at the API 6A standard for 6BX flanges and use the data there as a reference. There are alternate joint designs to the typical ASNI and ASME flanges in these pressure ranges, and one or more the manufacturers (of which I am one) would be happy to offer guidance.

rmorgan@ltsenergy.com

Rick

 

[TWP]

I did run (ASME-based)flange design calculations for NPS 14-Class 1500 RTJ WN flanges in order to determine MAWP and suitability for rating higher than Class 1500. Loading considered is internal pressure. No external forces/ moments taken into account. Details available upon request.